/ 1 January 2002

Flying snakes’ secret: they swim through the air

Birds flap their wings and other animals fly like gliders — but only snakes swim through the air, a biologist has found.

A study of the paradise tree snake has shown for the first time the extraordinary way the creature stays airborne. The Singapore snake, one of a family of flying snakes, has no wings or control surfaces.

But, ignoring conventional aerodynamics, it is able to soar with the greatest of ease – travelling distances of up to 100 metres and making mid-flight 90 degree turns.

Jake Socha, a biologist at the University of Chicago in the United States, has found that the snake does not fly through the air so much as swim.

It turns its body into a thin aerofoil by sucking in its stomach and generates lift by wriggling, as if swimming in water. For the study, Socha filmed and photographed snakes launching off a branch at the top of a 10-metre tower at Singapore Zoological Gardens.

He found that the snake prepared to take off by hanging from the branch, looping the front of its body into the shape of a ”J”. The snake then jumped, accelerating up and away from the branch. Its body flattened, roughly doubling in width, and began to undulate from side to side.

”While in flight, it not only flattens its entire body, it moves at the same time,” said Socha, who reported his findings in the journal Nature.

”It’s actually undulating in the air. So whatever muscles it?s using to flatten are probably decoupled from the muscles it’s using to undulate.”

Unlike most flyers, the paradise tree snake turns without banking. Instead, turns are initiated by movement of the front half of the body. Despite its strange flight behaviour, the snake’s aerial performance is on a par with that of other gliders such as flying squirrels, lizards and frogs.

Socha said the timing of the start of the undulations suggested that they generated lift.

There are five species of flying snakes which belong to the Colubridae family. Most grow three to four feet long and live in the lowland tropical rain forests of southern Asia. Scientists have only known about the creatures for the past century.

But legends of ”winged snakes” go back as far as the Greek historian Herodotus in the Fifth Century BC. Flying snakes are officially classified as harmless, but possess a mild venom which they used to kill small prey. – Sapa-DPA